Tubular drill and expansion anchor



g- 15, 6 A. FISCHER TUBULAR DRILL AND EXPANSION ANCHOR 3 Sheets-Sheet T.

Filed March 1965 INVENTOR ARTUR FISC HER g- 15, 1967 A. FISCHER TUBULAR DRILL AND EXPANSION ANCHOR 3 Sheets-Sheet Filed March 2, 1965 INVENTOR. ARTUR FISCHER Fig.11

United States Patent 3,335,632 TUBULAR DRILL AND EXPANSION ANCHOR Artur Fischer, Tumlingen, Kreis Freudenstadt, Germany Filed Mar. 2, 1965, Ser. No. 436,523 Claims priority, application Germany, Mar. 6, 1964, F 42,227; June 15, 1964, F 43,177; Aug. 1, 1964, F 43,645

4 Claims. (Cl. 85-68) The present invention relates to a tubular drill for drilling expansion anchor holes and a method of making and using the drill. The present invention relates especially to a tubular drill for drilling expansion anchor holes, in which part of the drill can be used after a bore has been drilled in a wall or the like as part of an expansion anchor arrangement.

Tubular drills for drilling a bore in a wall or the like are known, which after the bore has been formed by the drill are disconnected from the driving tool, and which after disconnection may be used as part of an expansion anchor arrangement by expanding the inner end of the tubular drill in the bore. The end of this drill is provided with an inner screw thread for connecting the rear end of the drill to a correspondingly threaded end of a percussion drill, so that after a bore has been drilled in a wall or the like, the percussion drillmay be disconnected from the threaded rear end of the drill and the latter be expanded in the bore to serve as an anchoring member. Experience, however, has shown that the unscrewing of the drill head from the percussion drill is sometimes very difficult, if not impossible.

The present invention aims to overcome the disadvantage of tubular drills of the aforementioned type known in the art.

It is an object of the present invention to provide a tubular drill for drilling expansion anchor holes in a wall or the like which can be easily connected to and disconnected from a driving tool, for instance a percussion drill.

It is a further object of the present invention to provide for a tubular. drill of the aforementioned type in which the drill head or the drilling portion of the drill may be easily severed from the driving portion thereof so that, after a bore has been drilled by the drill, the driving portion may be disconnected from the drilling .portion and the latter be used in the thus bored hole as part of an expansion anchor arrangement.

It is an additional object of the present invention to provide for a tubular drill of the aforementioned type in which the driving portion can be easily severed from the drilling portion after a bore has been drilled in a wall or the like and in which the drilling portion is constructed in such a manner that it can be left in the thus drilled bore and be expanded by a correspondingly shaped expansion means.

It is also an object of the present invention to provide for a method of manufacturing a tubular drill of the aforementioned kind which is provided with an inner screw thread at the drilling portion thereof so that a threaded bolt or the like may be connected to the drilling portion after the latter has been expanded in a bore drilled by the drill. v

With these objects in view, the tubular drill of the present invention mainly comprises an elongated tubular portion formed with a slot extending in longitudinal direction therethrough, a plurality of cutting teeth integral with the tubular portion and projecting in axial direction from one end thereof, and a driving projection integrally connected to the tubular portion in the region of the other end thereof and projecting outwardly therefrom.

Preferably, the tubular drill of the present invention comprises a tubular drilling portion having at one end a ICC plurality of cutting teeth projecting in axial direction therefrom, and a tubular driving portion coaxial with the tubular drilling portion and projecting integrally connected with the latter from the other end thereof, in which the portions of the drill are formed with a slot extending in longitudinal direction therethrough, in which the driving portion has an integral projection projecting in the region of the free end of the driving; portion outwardly from the latter, and in which the connection between the drilling portion and the driving portion is made in such a manner that the driving portion may easily be severed from the drilling portion so that the latter may be subsequently expanded in the bore drilled by the drill and used as part of an expansion anchor arrangement.

The weakened connection between the drilling portion and the driving portion of the drill may be made by forming at least one cutout extending from one face of the slot into the two portions and in which the cutout has its greatest depth in the region where the driving portion is joined to the drilling portion. In addition to the cutout, an annular groove may also be formed in the region of the deepest penetration of the cutout into the wall forming the drill, andthis annular groove is preferably provided at the outer surface of the drill to form at the same time an indication mark how far the drill should be driven into a wall or the like.

In a preferred arrangement the drilling portion is provided with a plurality of angularly spaced projections projecting from the inner surface thereof so that the drilling portion after the drill has been used for drilling a bore in a wall or the like may be left in the bore, and, after the driving portion is severed therefrom, be expanded in radial direction by driving a cylindrical expansion member from the outer end of the drilling portion into the latter and into engagement with the inwardly extending projections. The expansion member may be formed with a central bore therethrough provided with an inner screw thread so that the threaded end of a bolt or the like may be threadingly engaged into the threaded bore of the expansion member after the latter has been used for expanding the drilling portion in the bore of the wall. On the other hand, the drilling portion itself may be provided at its rear end with a screw thread so that the threaded end of a bolt or the like may be threadingly engaged directly with the drilling portion after the latter has been expanded at the front end. A combination of the two last mentioned features may also be provided so that bolts of diiferent diameters may be selectively used with the arrangement. r r

The longitudinal slot through the drill may be formed in such a manner that the opposite faces defining the slotare very close together at least in the drilling portion of the drill so that the greatest number of drilling teeth may be provided at the front end thereof and so that during rotation of the drill during the drilling operation jamming of the drill in the material of the wall will be avoided. The drill in this casernay also have an elongated intermediate portion between the drilling and the driving portion which has a smaller diameter than the aforementioned portions.

The method of manufacturing a tubular slotted drill according to the present invention having a drilling portion, an intermediate portion and a driving portion easily separable from the other portions and in which the intermediate portion is provided with an inner screw thread, mainly comprises the steps of forming a substantially rectangular fiat blank having a serrated end edge, a projecting portion projecting from a side edge of the blank at the end opposite the serrated end edge,and a weakened portion in the region where the driving portion joins the intermediate portion, embossing a plurality of parallel alternating grooves and ridges inclined at an angle of slightly less than 90 to the longitudinal axis of the blank into one face of the intermediate portion, and rolling the blank into a substantially cylindrical member so that the grooves and ridges will form an inner screw thread on the intermediate portion.

The method of using the drill according to the present invention mainly comprises the steps of driving a slotted tubular drill having a drilling portion and a driving portion, joined to the drilling portion in a manner so that said driving portion may be broken off from the drilling portion, into a wall or the like so as to form a bore in the wall having a length substantially equal to that of the drilling portion, breaking the driving portion from the drilling portion while the latter remains in the bore, and radially expanding the drilling portion by driving expansion means into the latter.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a front view of a blank from which a tubular drill of the present invention may be formed;

FIG. 2 is a front view of the tubular drill formed from the blank shown in FIG. 1;

FIG. 2a is a front view of an expansion member to be used in connection with the drill shown in FIG. 2;

FIG. 3 is a front view of another blank used for manufacturing a tubular drill of the present invention;

FIG. 3a is a cross section taken along the line III--III of the blank shown in FIG. 3;

FIG. 4 is a front view of a tubular drill formed from the blank shown in FIG. 3;

FIG. 4a is a top view of the tubular drill shown in FIG. 4;

FIG. 5 is a partly sectioned front view of a portion of the drill shown in FIG. 4 in a bore of a wall or the like with the inner end of the portion radially expanded by an expansion member;

FIG. 5a is a schematic view of the expansion member used in FIG. 5;

FIG. 6 is a partly sectioned front view of a different expansion member according to the present invention;

FIG. 7 is a front view of a further modification of a tubular drill according to the present invention;

FIG. 8 is a top view of the drill shown in FIG. 7;

FIG. 9 is a partially sectioned front view showing the use of the tubular drill illustrated in FIG. 7;

FIG. 10 is a partially sectioned front view of an additional modification of a drill according to the present invention; and

FIG. 11 is a partially sectional front view, showing part of the drill illustrated in FIG. 12 expanded in a bore of a wall or the like.

Referring now to the drawings and more specifically to FIGS. 1, 2 and 2a of the same, it will be seen that the tubular drill 1 illustrated in FIG. 2 comprises a drilling portion 3 formed at the front edge thereof with a plurality of substantially triangular drilling teeth 3a projecting in axial direction therefrom, an intermediate portion 2 which is provided with an inner screw thread 2a and a driving portion 1b having an integral projection 1a projecting outwardly from the tubular driving portion 1b. An annular groove 4b formed in the outer surface of the tubular drill in the region where the intermediate portion 2 joins the driving portion 1b weakens the cross section at this joint and further weakening is provided by a pair of substantially triangular cutouts 4 which extend from opposite faces of a longitudinal slot through the drill in the wall of the latter and each having their greatest depth in the region where the driving portion joins the intermediate portion.

The tubular slotted drill shown in FIG. 2 is preferably formed from a substantially rectangular flat blank, as shown in FIG. 1, having a serrated end edge 3a, a projecting portion 1a projecting laterally from a side edge of the blank at the end opposite the serrated end edge, and a weakened portion in the region where the portion 1b of the blank joins the portion 2. The weakened portion of the blank is formed by two substantially triangular cutouts 4 extending from opposite side edges into the latter and preferably also by an elongated groove 4b extending from the rear face of the blank into the latter. The front face of the intermediate portion 2 of the blank is provided with a plurality of closely spaced alternating grooves and ridges 2a, formed for instance by embossing, inclined at an angle of slightly less than to the longitudinal axis of the blank. The blank is then rolled into a substantially cylindrical member with the front face of the blank shown in FIG. 1 forming the inner surface of the cylindrical member, so that the grooves and ridges 2a will form an internal screw thread 2a on the intermediate portion of a slotted tubular drill shown in FIG. 2.

The tubular drill shown in FIG. 2 is used for drilling a bore in a wall or the like by connecting the driving portion 1b of the drill to a driving tool, for instance a percussion drill, which is provided with a tool holder formed with an appropriate cutout for locating the projection 1a of the driving portion therein. After a bore has thus been formed in a wall or the like, the tubular drill is removed from the bore, the driving portion 1b is severed, for instance broken off, from the intermediate portion 2, a frustoconical expansion member 8 as shown in FIG. 2a having a maximum diameter greater than the inner diameter of the drilling portion 3 of the drill is then placed at the bottom of the drilled bore so that when the portions 2 and 3 are driven into the bore over the expansion member 8, the front end of the drilling portion will be radially expanded and the portions 2 and 3 be fixedly held in the bore. The expansion member 8 is preferably formed with a central bore therethrough provided with an inner screw thread 8a so that after the expansion member and the portions 2 and 3 of the drill are fixedly held in the bore of the wall, the threaded end of a bolt or the like may be engaged with the inner screw thread 8a of the expansion member.

Another modification of the drill according to the present invention is shown in FIGS. 35a. The modification shown in these figures is very similar to that shown in FIGS. 1-211, and identical parts are designated with identical reference numerals. FIG. 3 shows a blank from which the drill shown in FIG. 4 is formed and this blank is identical with the blank shown in FIG. 1 except that the drill portion 3 of the blank is embossed at its rear face thereof so as to form at the front face thereof with a plurality of transversely spaced projections 3b, three such projections are shown in FIG. 3, which slightly project from the front face of the blank as best shown in FIG. 3a. The blank is then again rolled into a substantially cylindrical member as described before, to form the tubular slotted drill, as shown in FIGS. 4 and 4a, which differs from that shown in FIG. 2 by the projections 3b projecting angularly spaced from each other from the inner surface of the drilling portion 3 as best shown in FIG. 4a.

The drill shown in FIG. 4 is used in the aforementioned described manner for drilling a bore in a wall 6 or the like and the bore is drilled to a depth until the groove 4b formed in the outer surface of the drill is substantially flush with the outer surface of the wall. With the construction shown in FIGS. 3-5, the drill has not to be removed from the thus-drilled bore, but after the bore has been formed in the aforementioned manner, the connecting portion 1b is simply broken off from the intermediate portion 2 while the intermediate portion and the drilling portion 3 are left in the bore. A substantially cylindrical member 5 having an outer diameter substantially equal to the inner diameter of the portions 2 and 3 is then driven into the portions of the drill left in the bore and into engagement with the projections 3b so that the drilling portion 3 is radially expanded, whereby the portions 2 and 3 of the drill left in the bore and the expansion member 5 are securely fixed in the bore. The cylindrical expansion member 5 may also be formed with a central bore therethrough provided with an inner screw thread 5a, so that after the aforementioned members are fixed in the bore of the wall screw bolts having a threaded end meshing with the screw thread 5a ofthe expansion member 5 or meshing with the screw thread 2a of the portion 2 of the drill may be selectively connected thereto, respectively.

FIGS. 6-9 show further modification of a slotted tubular drill according to the present invention and especially FIG. 9 shows the use of the drill.

The longitudinal-1y slotted tubular drill 11 shown in FIG. 7 comprises a tubular drilling portion 13 formed at the front end thereof with a plurality of substantially triangular drilling teeth 13a projecting in axial direction from the front end of the drilling portion 13, and a driving portion 11b coaxial with and integrally joined with the drilling portion 13. The driving portion 11b has a driving projection 11a, projecting from one face of the longitudinal slot substantially tangential to the cylindrical driving portion outwardly therefrom. An annular groove 14b is formed at the outer surface of the drill in the region where the drilling portion 13 joins the driving portion 1112. A pair of substantially triangular cutouts 14 are also provided respectively extending from opposite faces of the slot, each of the cutouts has its greatest depth in the region of the groove 14b, and each of the cutouts has a pair of side faces of different length, the longer side face 14a being arranged in the driving portion and is inclined to the axis of the drill at a smaller angle than the other side face of the cutout.

The driving portion 11b of the drill 11 is connected to a tool holder portion 7 of a percussion drill 9 schematically indicated in FIG. 9 and the drill 11 is used to drill a bore in a wall 6 or the like. After the bore is formed, the driving portion 11a is broken off or otherwise severed from the drilling portion 13 and the front end of the latter is expanded by appropriate expansion means to securely fasten the drilling portion 13 in the bore of the wall. It is to be understood that if a frustoconical expansion member 8 as shown in FIGS. 6 and 9 is used for expanding the front end of the drilling portion 13, the drilling portion has to be retracted from the bore in the wall after the bore has been drilled, the expansion member 8 has to be subsequently thereto placed into the bore, whereafter the severed drilling portion is driven over the expansion memberS into the bore to expand the front end of the drilling portion in radial direction. The groove 14b and the cutouts 14 not only serve to facilitate severing or breaking off of the driving portion from the drilling portion, but the groove and the cutouts will also form indication marks to clearly indicate to the operator of the tool how far the tubular drill should be driven into the wall 6.

FIGS. -11 show a further modification of the slotted drill according to the present invention.

In order to prevent wedging of material into the longitudinal slot of the tubular drill during the drilling operation, which would detrimentally affect the efiiciency of the drilling operation, the longitudinal slot and the tubular drill shown in FIGS. 10 and 11 are formed in such a manner that the opposite end faces defining the slot are very closely spaced from or abut against each other at least at a part of the drilling portion of the drill.

FIG. 10 shows a further modification of the drill of the present invention and the drill 31 shown in FIG. 10 has a drilling portion 33 formed at the front edge thereof with substantially triangular teeth 33a, and a driving portion 33b arranged coaxially with the drilling portion and integrally connected thereto. The driving portion 31b is again provided with a driving projection 31a. The drill 31 is formed in the region where the drilling portion 33 is joined to the driving portion 31b with an annular groove 34 providing a weakened joint so that the driving portion may be broken off from the drilling portion 33, after the drill has been used for boring a hole in a Wall or the like, so that the drilling portion may be used as part of an expansion anchor arrangement in the bore. The drilling portion 33 is preferably provided with an inner screw thread 32a at least at a part thereof extending from the groove 34 toward the serrated end edge of the drilling portion. The drill 31 shown in FIG. 10 is provided with a longitudinally extending slot 330 and this slot is narrowed at 33b at least at a portion thereof extending from the groove 34 toward the serrated front edge of the drilling portion 33.

The drill 31 shown in FIG. 10 is used for drilling a bore in a wall 6 or the like, and during the drilling operation the drill is driven into the wall to a depth so that the groove 34 will be flush with the outer surface of the wall. Subsequently thereto the driving portion is severed, for instance by breaking the same off from the drilling portion, and the drilling portion 33 left in the bore of the wall is expanded by expansion means 40 as shown in FIG. 11. The expansion means 40 shown in FIG. 11 preferably comprise a frustoconical member having a maximum diameter substantially equal to the inner diameter of the drilling portion 33, and a partly slotted cup-shaped memher which is inserted in the drilling portion and then wedged over the frustoconical expansion member, thereby expanding the inner end of the drilling portion.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of tubular drills differing from the types described above.

While the invention has been illustrated and described as embodied in a tubular slotted drill for drilling expansion anchor holes in a wall or the like and in which a portion of the tubular drill may be used as part of an expansion anchor arrangement, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A tubular drill for expansion anchor holes comprising, in combination, a tubular drilling portion having at one end a plurality of cutting teeth projecting in axial directions therefrom; and a tubular driving portion coaxial with said tubular drilling portion and projecting integrally connected to the latter from the other end thereof, said portions being formed with a slot extending in longitudinal direction therethrough, said driving portion having an integral projection projecting in the region of the free end of the driving portion outwardly from and tangential to the latter, the connection between said drilling portion and said driving portion being made in such a manner that said driving portion may be easily severed from said drilling portion so that the latter may be subsequently ex- '7 panded and then be used as part of an expansion anchor arrangement.

2. A tubular drill for expansion anchor holes comprising, in combination, a tubular drilling portion having at one end a plurality of cutting teeth projecting in axial direction therefrom, said drilling portion being provided with an internal screw thread at a part thereof adjacent its other end and in the region of said one end thereof with a plurality of inwardly extending projections; and a tubular driving portion coaxial with said tubular drilling portion and projecting integrally connected to the latter from the other end thereof, said portions being formed with a slot extending in longitudinal direction therethrough, said driving portion having an integral projection projecting in the region of the free end of the driving portion outwardly from and tangential to the latter, the connection between said drilling portion and said driving portion being made in such a manner that said driving portion may be easily severed from said drilling portion so that the latter may be subsequently expanded by engagement of said inwardly extending projections with a cylindrical pressure member driven into said drilling portion and then be used as part of an expansion anchor arrangement.

3. A tubular drill for expansion anchor holes comprising, in combination, a tubular drilling portion having at one end a plurality of cutting teeth projecting in axial direction therefrom; and a tubular driving portion coaxial with said tubular drilling portion and projecting integrally connected to the latter from the other end thereof, said portions being formed with a slot extending in longitudinal direction therethrough, said driving portion having an integral projection projecting in the region of the free end of the driving portion outwardly from the latter, said slotted drill being formed with at least one cutout extending from one face of said slot into said portions, said cutout having its greatest depth in the region where said driving portion is joined to said drilling portion so as to provide at the joint a weakened portion facilitating breaking said driving portion off from said drilling portion after said drill has been used for drilling a hole in a wall or the like so that drilling portion may be subsequently expanded and then be used as part of an expansion anchor arrangement.

4. A tubular drill for expansion anchor holes comprising, in combination, a tubular drilling portion having at one end a plurality of cutting teeth projecting in axial direction therefrom; and a tubular driving portion coaxial with said tubular drilling portion and projecting integrally connected to the latter from the other end thereof, said portions being formed with a slot defined by a pair of opposite faces and extending in longitudinal direction therethrough, said driving portion having an integral projection projecting in the region of the free end of the driving portion outwardly from the latter, said drill being formed in the region where said driving portion joins said drilling portion with an annular groove and a cut-out in the region of intersection of said groove with said slot so as to facilitate severing of said portions from each other and said opposite faces of said slot nearly engaging each other along a part of said drilling portion extending from said groove toward said one end of said drilling portion.

References Cited UNITED STATES PATENTS 1,752,752 4/1930 Ogden 35 -74 1,762,349 6/1930 Phillips s5 63 1,996,121 4/1935 Phillips 68 2,406,536 8/1946 Gelpcke 85-68 3,032,657 3/1963 Fischer s5 72 3,123,370 3/1964 Unander 35 6s FOREIGN PATENTS 137,806 9/1920 Great Britain.

569,774 6/1945 Great Britain.

429,532 1/1948 Italy.

CARL W. TOMLIN, Primary Examiner.

M. PARSONS, JR., G. A. MILWICK,

Assistant Examiners. 

1. A TUBULAR DRILL FOR EXPANSION ANCHOR HOLES COMPRISING, IN COMBINATION, A TUBULAR DRILLING PORTION HAVING AT ONE END A PLURALITY OF CUTTING TEETH PROJECTING IN AXIAL DIRECTIONS THEREFROM; AND A TUBULAR DRIVING PORTION COAXIAL WITH SAID TUBULAR DRILLING PORTION AND PROJECTING INTEGRALLY CONNECTED TO THE LATTER FROM THE OTHER END THEREOF, SAID PORTIONS BEING FORMED WITH A SLOT EXTENDING IN LONGITUDINAL DIRECTION THERETHROUGH, SAID DRIVING PORTION HAVING AN INTEGRAL PROJECTION PROJECTING IN THE REGION OF THE FREE END OF THE DRIVING PORTION OUTWARDLY FROM AND TANGENTIAL TO THE LATTER, THE CONNECTION BETWEEN SAID DRILLING PORTION AND SAID DRIVING PORTION BEING MADE IN SUCH A MANNER THAT 